A prominent neoconservative intellectual and early promoter of the Iraq War is headlining an official campaign fundraiser for Hillary Clinton next month, Foreign Policy has learned. The move signals a shift in the Clinton campaign's willingness to associate with prominent Republicans and is the latest sign of how far GOP defectors are willing to go to block a Donald Trump presidency.

Robert Kagan is an American historian and foreign policy commentator. He is a senior fellow at the Brookings Institution and an adjunct professor of history at Georgetown University, and was listed by Foreign Policy and Prospect as one of the world's "Top 100 Public Intellectuals". (Photo by Brooks Kraft LLC/Corbis via Getty Images)

A prominent neoconservative intellectual and early promoter of the Iraq War is headlining an official campaign fundraiser for Hillary Clinton next month, Foreign Policy has learned. The move signals a shift in the Clinton campaign’s willingness to associate with prominent Republicans and is the latest sign of how far some GOP defectors are willing to go to block a Donald Trump presidency.

Robert Kagan, a senior fellow at the Brookings Institution and a co-founder of the Project for the New American Century, will speak at a Hillary for America fundraiser in Washington’s Logan Circle neighborhood on July 21. According to an invite obtained by FP, the “event will include an off-the-record conversation on America’s continued investment in NATO, key European allies and partners, and the EU.”

Kagan did not immediately respond to a request for comment.

The Clinton campaign has made clear it believes Trump’s high unfavorable ratings and provocative comments have created an opening for her candidacy among traditional GOP voters, and will soon begin actively courting the Republican electorate.

The campaign has been careful about such overtures in the past as it fended off criticisms from the left by her primary rival Bernie Sanders, who highlighted her 2002 vote in favor of the Iraq War, ties to controversial Republican figures like Henry Kissinger, and warm relationship with Wall Street.

“In her book and in this last debate, she talked about getting the approval or the support or the mentoring of Henry Kissinger,” Sanders said during a February debate. “Now, I find it rather amazing, because I happen to believe that Henry Kissinger was one of the most destructive secretaries of state in the modern history of this country.”

While dozens of Republican foreign-policy insiders have publicly renounced Trump, far fewer have announced their support for Clinton. But cracks are beginning to emerge.

On Wednesday, Clinton picked up the endorsement of Republican Brent Scowcroft, who served as a national security adviser to Presidents George H.W. Bush and Gerald Ford, and held formal or advisory positions in the administrations of former Presidents Richard Nixon and George W. Bush.

“She brings deep expertise in international affairs and a sophisticated understanding of the world, which I believe are essential for the commander-in-chief,” Scowcroft said in a statement.

But while Scowcroft hails from the GOP’s realist school of thought, a less-interventionist worldview that some liberals subscribe to, Kagan remains firmly in the neoconservative wing — an ideology centered around the use of military force, the forcible removal of dictators, and the importance of spreading democracy around the world.

During the heat of the Democratic primary campaign, prominent Sanders supporters sought to tie Clinton to the more hawkish foreign policy of Kaganand other neoconservatives, noting his favorable remarks toward the former first lady.

“I feel comfortable with her on foreign policy,” Kagan told the New York Times in 2014. “If she pursues a policy which we think she will pursue it’s something that might have been called neocon, but clearly her supporters are not going to call it that; they are going to call it something else.”

In more recent years, Kagan has loudly criticized the Obama administration for not intervening more forcefully in the five-year civil war in Syria or pushing back more aggressively against Russia in the Ukraine conflict. He routinely calls for defense spending to take up a larger share of the federal budget. Many of his beliefs were encapsulated in his New Republic cover story “Super Powers Don’t Get to Retire” advocating for an expansive U.S. diplomatic and military presence around the world.

As a staunch defender of NATO, Kagan’s views clash starkly with Trump, who has called the military alliance “obsolete” and castigated European allies for failing to pay at least two percent of their gross domestic product on defense — a benchmark that the vast majority of the 28 NATO members have failed to meet. Clinton, meanwhile, has been an outspoken defender of NATO in recent speeches.

Kagan is also the husband of Victoria Nuland, who served as the spokesperson for the State Department during Clinton’s tenure as secretary of state, and is currently the assistant secretary of state for European and Eurasian Affairs. Internally, Nuland has pressed the Obama administration to play a more aggressive role in the Ukraine conflict.

A ticket to the event at the Cambria hotel rooftop is $100. A VIP ticket, which includes access to a reception with the event’s speakers and hosts, costs $250. It costs $500 to earn the title of “host.”

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John Hudson is a senior reporter at Foreign Policy, where he covers diplomacy and national security issues in Washington. He has reported from several geopolitical hotspots, including Ukraine, Pakistan, Malaysia, China, and Georgia. Prior to joining FP, John covered politics and global affairs for the Atlantic magazine’s news blog, the Atlantic Wire. In 2008, he covered the August war between Russia and Georgia from Tbilisi and the breakaway region of Abkhazia. He has appeared on CNN, MSNBC, BBC, C-SPAN, Fox News radio, Al Jazeera, and other broadcast outlets. He has been with the magazine since 2013. @john_hudson